Have a look into sulfur. I dont believe increasing or decreasing Iodine will make much difference. There is more to it. Like when / if the sulfur cycle is broken (chemical fertilizers etc., the minerals simply arent utilized properly.
"Chondoitron and glucosamine are sulfur based amino acids, and sulfur is the "glue" which not only forms the matrix of our bones and joints but all of the cellular interlinking which is the true cellular matrix not only of man but all living organisms, even water has a matrix. The pines from which MSM comes from stand straight and tall due to the sulfur which bonds their cells together." http://cellular-oxygenation.com/Organic_Sulfur_Study.html#.VLQUQyuG-So